Today's portable communication devices, operated in a public safety environment, often utilize a plurality of microphones for noise cancellation of background noise. Some microphone arrangements also need to be mounted in pairs to provide beam forming (directivity to source/user). Unlike sealing and porting needs of a singular microphone, the porting and sealing of a plurality of microphones face different acoustical problems and physical implementation challenges. Product use requirements, in combination with the technical requirements of noise canceling algorithms, require that microphones be properly positioned with respect to each other.
Some microphone array arrangements are challenged with alignment between microphones in the z-direction (thickness of the product), such as in handheld radio applications where the device is held away but facing the user. FIG. 1 is a microphone porting structure 100 in accordance with the prior art. While the porting structure 100 provides space saving for top ported microphones 102, 104 mounted to a printed circuit board (pcb) 106 and establishes a noise cancelling vector that is normal to the pcb, however the outward porting makes these devices difficult to seal and the acoustic performance tradeoffs associated with top ported microphones makes them undesirable, particularly for beam forming applications.
Accordingly, there is a need for improved microphone porting. Improved microphone porting that would further facilitate the ability to seal the microphone in a portable communication device would be a further desired benefit.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.